Channel construction for industrial truck



May 10, 1960 F. A. VOSSENBERG 2,936,044

CHANNEL CONSTRUCTION FOR INDUSTRIAL TRUCK Filed Feb. 19, 1957 5Sheets-Sheet 1 INVENTOR. fr? I OJJUA/Qff BY a -d MLI May 10, 1960 F. A.VOSSENBERG 2,936,044

' CHANNEL CONSTRUCTION FOR INDUSTRIAL TRUCK Filed Feb. 19, 1957 5Sheets-Sheet 2 May 10, 1960 F. A. VOSSENBERG 2,

CHANNEL CONSTRUCTION FOR INDUSTRIAL TRUCK Filed Feb. 19, 1957 5Sheets-Sheet 3 I N VEN TOR.

ozrle 5/417 arrow/1 May 10, 1960 F. A. VOSSENBERG 2,936,044

CHANNEL CONSTRUCTION FOR INDUSTRIAL TRUCK Filed Feb. 19, 1957 I 5Sheets-Sheet 4 l I I I finite Frank A. Vossenberg, Stralford, Pa.,assignor to The Yale 8: Towne Manufacturing Company, Stamford, Conn., acorporation of Connecticut Application February 19, 1957, Serial No.641,087

7 Claims. (Cl. 187-9) This invention relates to an industrial truck ofthe type adapted to handle extremely large and heavy loads and to liftthose loads to considerable heights. There are numerous trucks on themarket designed for this purpose, these trucks generally involving fixedor primary uprights on which are movably mounted secondary uprights, thesecondary uprights in turn having mounted thereona carriage. The load ishandled by the carriage through forks or a platform, the carriage movingon the secondary uprights, and the secondary uprights in turn moving onthe primary or fixed uprights. For imparting lifting movement to thecarriage there is utilized a ram, the ram operating generally throughchains to impart lifting movement to the carriage.

Because the loads are extremely heavy and are handled at one end of thetruck, the stresses carried by the uprights and carriage and variousother parts are extremely large. Therefore, the channels forming theprimary and secondary uprights are quite large in section. Since thehydraulic ram is also large, and since there maybe required two rams,the result is that the alignment of the rams and uprights effectivelyblocks the vision of the operator in handling the load.

Much effort and thought has been applied'to the problem of providinggood vision to the operatorin a truck of the particular class, but sofar as I know, no one has been successful in meeting the problem.

' In'the handling of lighter loads, it is possible to use a primary orfixed upright that is formed as a channel,

being U-shaped with the bottom of the U parallel to the longitudinalaxis of the truck. The secondary upright can be similarly shaped and canetfectively nest Within the primary upright for movement relativelythereto.

However, when heavy loads are applied, the friction developed betweenthe primary upright and the secondary upright is so great that theconstruction cannot be utilized. Those skilled inthe art have long knownthat a construction of the particular class might very well be used ifrollers could be applied between the primary and secondary uprights foraccepting the thrust between the two in an effective manner. So far as Iknow, no one has yet been able to solve the problem of the applicationof rollers or other anti-friction means.

Because those skilled in the art have been unable to solve this problem,it has been the'custom in the art to mount the secondary uprights andthe primary uprights in juxtaposed relation to one another with rollerson the secondary uprights moving in the channels of the primaryuprights. Obviously, this means thatthe flanges of the uprights extendtransversely of the truck and most efiectively block the vision of the,operator.

ice

less transversely of the truck,so as to block a great deal of the visionof the operator, while also lengthening the truck somewhat. Further, thestresses are so disposed that there is a tendency to twist the uprights,particularly were extremely heavy loads to be handled. It is obviousthat the construction is not nearly so effective as a construction inwhich the uprights are in nested relation.

Various other constructions have been proposed, including an offsetjuxtaposed positioning of the uprights, but all of these constructionsfail for one reason or another and have never been deemed successful.

The concept that I contribute to the art through this applicationinvolves the use of nested uprights, but with the secondary uprightsmoving relatively to the primary uprights on rollers that functioneffectively because of the positioning of the secondary uprightsrelatively to the primary uprights, and because of the effect of theload carried by the secondary uprights. Thus, the secondary uprights areadapted to cock or tilt relatively to the primary uprights within thechannel of the primary uprights in which they slide, suflicient spacebeing provided for this purpose. By providing rollers that will acceptthe forces introduced by this tendency to tilt or cock, I am able tomount the secondary uprights in nested relation to the primary uprights.Further, the channels of the secondary uprights remain free to houserollers for the mounting of a load carriage thereon.

As a particular feature of my invention, the secondary uprights carryrollers at their lower ends and the primary uprights carry rollers attheir upper ends. In this way, the rollers at the lower ends of thesecondary uprights are always in a'position to accept forces between theprimary and secondary uprights at one end of the secondary uprights. Theprimary uprights carry their rollers at their upper ends, and therebyare adapted to accept the stresses between the primary and secondaryuprights at one end of those portions of the secondary uprights withinthe primary uprights. Of course, the cocking of the secondary uprightsrelatively to the primary uprights maintains the rollers always ineffective position to accept the thrusts or forces between the uprights.a

As a further particular feature of the invention, the

secondary uprights have some play within the channel of the primaryuprights so that actually the secondary uprights will cock within thechannels of .the primary uprights, the rollers then being positioned inwhat might be considered an angular relationship to one another so as toaccept the thrusts between the two uprights.

An actualoperating truck has been constructed in ac cordance with myconcept and is extremely eflective in An attempt has been made duringthe last few years to mount the uprights with the flanges of thesecondary operation, being adapted to handle extremely heavy loads andto move those loads into an extremely high position. Because I am ablethrough my construction to nest the uprights within one another, I amable to obtain extremely good vision for the operator. The importance ofthe construction may be well appreciated if it is understood that evenif the flanges of the secondary uprights are only 3 inches in width andthe primary uprights 3 /2 inches, the four flanges will presentto theoperator approximately 13 inches. This, together with the rams,-w illeifectively block the vision of the operator. Bynesting the secondaryuprights within the Plii mary uprights, I am able to free to theoperator at least 6 inches of vision, which, in the center of the truckis of great significance. I "As a further feature of my invention, I amable to provide rollers for accepting also the side or transverse thrustof the secondary uprights relatively to the. pri

. mary uprights.

uprights in a somewhat offset relationship, but neverthe A still furtherfeature of the invention resides in the mounting of the two rams, lowerend through resting on a small protuberance carried by the primaryuprights, the pistons of the rams being secured to .the upper ends ofthe secondary up.- rights. 7

As a still further feature of the invention, the secondary uprightscarry the load sheaves operating against the chains that in turn movethe carriage. Since the thrust of the rams is accepted by thesecondary.uprights directly, I am able to mount the load sheaves inofiset relation to the rams while still efiectively balancing the loadscarried by the rams without subjecting the rams and secondary uprightsto offset stresses. 7

A further feature of the invention resides in the forming of guides orsupports on the secondary uprights for mounting the rams on thesecondary uprights prior to the assembly of the secondary uprights tothe primary uprights.

As a further feature of the invention, each ram is held against rotationand movement off its seat through the utilization of a part that allowsfree movement of each ram on its seat while holding the ram againstrotation, the particular parts being carried by the fixed uprights. As afurther feature of the invention, the primary uprights are mounted forrotation on a fixed axis through novel bearing means that areinterlocked relatively to the shaft forming the tilt axis. 7

A still further feature of the invention resides in the manner in whichthe main frame of the truck is se-' cured to the traction axle, thefeature of this construction being the relation of the parts so as toallow the placing of the tilt axis of the uprights, in as close relationto the axis of the traction wheels as is possible. This means that theuprights are mounted as closely to the fulcrum axis about which theytend to tip the truck as it is possible to place them.

A still further feature of the invention'r'esides in the mounting of thecarriage relatively to the secondary uprights. This constructionutilizes a pair of plates each carrying rollers moving in the channel ofthe secondary uprights. The load forks fit between the two plates andare then secured to the plates through spacers, the number of spacersused and their thickness being adapted to determine the spacing of theplates and their adjustment relatively to the secondary uprights. Thisallows for very accurate mounting of the carriage while yet makingpossible the manufacture of theparts with commercial standards.

I have thus outlined rather broadly the more important features of myinvention in order that the detailed description thereof that followsmay be better understood, and in order that my contribution to the artmay be better appreciated. There are, of course, additional features ofmy invention that will be described hereinafter and which will form thesubject of the claims appended hereto. Those skilled in the art willappreciate that the conception on which my disclosure is based mayreadily be utilized as a basis for the designing of other structures forcarrying out the several purposes of my invention. It is important,therefore, that the claims be regarded as including such equivalentconstructions as do not depart from the spirit and scope of myinvention, in order to prevent the appropriation of my invention bythose skilled in the art.

Referring now to the drawings, Fig. l is a plan view and partial sectionof one end of an industrial truck, showing the upright and load liftingassembly of my invention with relation thereto. v

Fig. 2 is a side view of the parts of Fig; Land illustrates thearrangement of the uprights,'their mounting on the transmission of thetruck, together with the application of the forks to the load liftingcarriage.

Fig. 3 is a vertical end view and partial section of the uprightassembly as applied 'to the truck.

each ram being carried at its Fig. 4 is a side view of the primaryupright assembly of my invention broken away at its center to shortenthe drawing.

Fig. 5 is a front elevation of one-half of the primary upright assemblyof Fig. 4.

Fig. 6 is a plan view of that half of the upright assembly shown in Fig.5.

Figs. 7 and 8 are diagrammatic views illustrating the relationship ofthe primary and secondary uprights in two positions of the secondaryuprights relative to the primary uprights.

Fig. 9 is a side view of the secondary upright assembly, while Fig. 10is an elevation of that assembly.

Fig. 11 is a section taken along the lines 11-11 of Fig. 10.

Referring now more particularly to the drawings, and especially thediagrammatic views of Figs. 7 and 8, the primary upright assembly isdesignated by'reference numeral 10, while the secondary upright assemblyis desig: nated by reference numeral 11. The primary upright assembly 10is best shown in Figs. 4, 5 and 6, while the secondary upright assembly11 is best shown in Figs. 9, 10 and 11. In Fig. 7 the secondary uprightsare in their lowermost position within the primary uprights and as thereshown, the secondary uprights have assumed a slight angular positionwithin the primary uprights. Of course, this angular position isextremely exaggerated since in my actual construction the play betweenthe primary and secondary uprights is one-quarter of an inch. In otherwords, the secondary uprights may move transversely within the channel,of the primary uprights for a distance of one-quarter of an inch. Asuitable roller 12, to be referred to more specificallyhereinaften'is'carried at each side of the lower end of the secondaryupright. A roller 13 is carried at the upper end of each side of theprimary upright. The load that is imposed on the secondary uprightassembly will bias the secondary uprights to the angular positionillustrated in Fig. 7 so that the lower end of the secondary uprightswill carry each roller 12 against a flange surface of the channels ofthe primary uprights 10 as there shown. As the secondary uprights movein the primary uprights, as to the position shown in Fig. 8, the roller12 will accept the stresses between the two uprights and will preventthe development of friction. Of course, the rollers 13 at the upper endsof each primary upright will accept the thrust between the secondaryuprights and the primary uprights in the opposite direction, as is wellshown in Fig. 8 as well as Fig. 7, thereby effectively mounting thesecondary uprights within the primary uprights for free slidingmovement.

I thought it well to refer first to the diagrammatic views. of Figs. 7and 8 because a full understanding of those views will facilitate theunderstanding of the actual construction that will be described fully.It is well to indicate also that each roller 12 is so positioned that itwill effec-: tively accept about one-eighth of an inch or one-half ofthe play between the secondary and primary uprights, while the roller 13is also adapted to accept about oneeighth of an inch or one-half theplay. In view of this, it is possible under certain circumstances forthe sec ondary uprights to move relatively to the primary uprights for adistance'of.approximately one-eighth of an inch, and such movement mayconceivably occur when the truck is stopped suddenly or acceleratedsuddenly with the load in a particular position. conceivably, it mightbe desirable to have pressure rollers carried: on the primary uprightsfor preventing violent shifting of the secondary uprights even throughthis small distance of one-eighth of an inch. In the actual truck that Ihave constructed I have not found this necessary as yet.

Referring now to Figs. 4, 5 and 6, I shall describe the primary uprightassembly of my invention. It will be noted from Figs. 5 and 6 that Ishow, for convenience, only one-half of the upright assembly, sincethe-assembly is symmetrical. The upright assembly will comprise a pairof U-shaped channels that are connected at their lower ends by asuitable bottom cross-plate 16 and other reinforcing structure,including a vertical plate 17. The upper ends of the channels 15 will bebraced by a structural member 18 welded to a cylindrical bracing pipe 19that is in-turn braced by gussets 2t) welded to a crossangular member21. The manner of bracing and holding the channels 15 assembled is notof importance to my invention, and is here merely described in orderthat there may be an understanding of the specific structure I havedevised. It is only required to understand that I use a pair of channelssuitably connected for accepting the heavy stresses applied thereto. Atone end of the structural member 18 on each side of the truck there is asuitable bearing 24 for a roller 13, this being the roller that wasearlier referred to in connection with Figs. 7 and 8. One roller 13 isalso well illustrated in Fig. 2 where it is shown in position to acceptthe thrust of the secondary uprights 11. The members 18 are also adaptedto support side thrust rollers 22 to bear at the sides of the secondaryuprights 11, as will be understood after reading the specification thatfollows.

Referring now to Figs. 9, 10 and 11, 'I show the secondary uprightassembly. This assembly comprises a pair of channels 25 suitablyconnected at their lower ends by a vertical'cross-bar 2'6, and at theirupper ends by a compound cross-bar 27. An intermediate vertical crossbar28 is also utilized. In addition, a box-like structure is carried at theupper end of the upright assembly and comprises four vertical members 29and a cross-plate 30. The cross-plate 30 is formed with openings throughwhich may extend lugs 31 at the ends of pistons 32 of a pair ofhydraulic rams 33, the rams being best illustrated in Figs. 2 and 3. Thecross-plates 26 and 28 carry suitable brackets 34 best shown in Fig. 11,these brackets being adapted to hold in place the rains 33, those ramsbeing moved upwardly into posit-ion between brackets 34 as depicted byarrows a in Fig. 10. This permits the secondary upright assembly 11 to:be moved with facility into nested relation to the primary uprightassembly 10 by the placing of the channels 25 into nested relation tothe channels 15, as best shown in Fig. 1. In Fig. l, I show the nestedrelation of the upright assemblies at one side of the truck, but sincethe truck is symmetrical, as was earlieremphasized, this will suffice toshow clearly the construction.

When the secondary upright assembly 11 is nested within the primaryupright assembly 10, the lower ends of the rams 33 are adapted to reston buttons 35 carried by the plate 16 of the primary upright assembly.Naturally, dwells are formed in the lower ends of the rams 33 so thatthey may rest on the dome-shaped buttons 35, permitting some freemovement of the rams, as will be understood and appreciated by thoseskilled in the art. Each ram is equipped with a nozzle construction 36best illustrated in Figs. 3 and 5, and I utilize this nozzle both forthe purpose of leading hydraulic fluid to the ram 33, and also toposition each ram within the truck assembly. Thus, a securing plate 37is bolted at 38 to dross-member 17, as well shown in Fig. 5. The platehas a relatively large opening 39 that fits freely about the nozzle 36,thereby allowing some free movement of the nozzle and its ram relativelyto the plate 37. The opening 39 is sufiiciently small with relation tothe nozzle 36 so that the ram will not be permitted, however, to moveoff its seat on dome-shaped button 35. Of course, each of the two ramsof my truck assembly is mounted in this manner. I

Referring now once again to Figs. 9, 10 and 11, it will be noted that atthe lower end of the upright assembly, provision is made for. themounting of bearing rollers 12 referred to earlier in connection withFigs. 7 and 8. These are, of course, the rollers that accept the thrustbetween the lower end of the secondary upright assem bly and the primaryuprights due to the biasing of the sides of the channels 15 forming theprimary upright assembly, it being obvious that the rollers 40 accepttransverse stresses, coating for this purpose with the rollers 22mounted at the upper ends of the primary uprights. It will be well atthis time also to refer to Fig. 2 wherein the relationship of therollers 12 and 13 is further well illustrated and set forth. Fig. 2 isalso helpful in showing the secondary uprights nested within the primaryuprights, as well as the relation of the rams to the secondary andprimary uprights.

Fig. 2 is now referred to again in order to describe the manner in whichthe entire upright assembly is mounted on the truck. For the purposes ofmy invention, the truck is shown formed with a banjo housing 42, thehousing having at each end a square extension 43 in which is mounted adrive axle, this axle being of the usual type required in vehicles ofthis class. I have arranged to at tach my upright assembly to the truckthrough a pair of bracket constructions, there being onebracketconstruction for each square portion at each side of the banjo housing.More in detail, a bracket 44 is securely welded to each side of theprimary upright assembly and is formed with a partial bearing 45. Thisconstruction is also well illustrated in Fig. 4. Coacting with thebracket 44 is a second bracket 46 that is adapted to be secured by abolt 47 to the primary uprights, and by a second bolt 43 t0 the bracket44. Further, the bracket 46 has a lug portion 49 interlocking with a lug50 of the bracket 44, as well as a bearing surface 45a cornplementary tosurface 45. The purpose of this construction is to cause the bracketportions 46, 44 to accept between them a shaft 51. any tendency toseparate the two brackets 44, 46 will be resisted not only by the bolts47, 48 but also by the interlocking lugs 49, 50, as will be wellappreciated.

Naturally, because of this construction, the entire up right assembly isadapted through the brackets 44, 46 to rotate or pivot on the shaft 51.The shaft 51 is in turn carried by a pair of interlocking brackets 52,53 that are adapted to embrace each of the square axle housingextensions 43 earlier set forth. In other words, the shaft 51 issupported by the brackets 52, 53 and shaft 51 in turn carries theprimary upright assembly so that assem bly may pivot. A suitable bracket54, best shown in Figs. 4 and 5, is secured at each side of the primaryupright assembly 19, and is formed with an opening 55. It is the purposeof the openings 55 of the bracket 54 to mount a pair of rams for tiltingthe uprights. 'Since' the particular tilting construction isconventional, it is not described further.

I shall now refer to Figs. 1, 2 and 3 to describe the load carriage ofmy truck. The carriage has on each side thereof a vertical plate 57which carries upper and lower rollers 58, as best seen in Fig. 2, therollers on these plates 57 moving in the channeled uprights 25-of thesecondary upright assembly 11. This mounting of the plates 57 on thesecondary uprights is substantially conventional as those skilled inthe'art will appreciate. The two vertical plates 57 are thenassembled-to the remainder of the carriage in novel fashion. Thus,referring to Figs. 1 and 2, I have upper and lower brackets 59 and 59awelded to form an integral part of upper and lower carriage members 61and 61a. These, brackets 59, 59a are bolted to the plates 57 throughbolts 60-,

When this shaft is embraced,

upright channels.

7 upright channels 25, and by decreasing the thickness of the shims theplates are moved away from the secondary In this most simple manner, Iam able to adjust the position of the rollers 58 without difficulty.

As is required in the art, the upper and lower carriage members 61, 61asupport forks designated by reference numeral 65 in Fig. 2. Each fork isequipped with upper and lower brackets 66 having lug portions 67 adaptedto coact with a vertically extending longitudinal rib 68 on each of themembers 61, 61a. It is the purpose of this construction to position theforks on the carriage. In addition, the forks have means whereby theymay be secured in any one of a series of transversely spaced positions.This is accomplished through the utilization of dogs 70, shown in Fig.2, adapted to fit into slots 69 formed in the upper longitudinallyextending rib 68.0f the upper carriage member 61. Each dog 70 is formedas part of lever 71 pivoted at 72 to a fork 65. The levers 71 areequipped with handles '73 whereby they may be pivoted on axis 72. Thus,in order to release the forks for sliding movement relative to the upperand lower carriage plates 61, 61a, the handles 73 rotate the leverscounter-clockwise, moving the dogs 70 out of the slots 69. Thereupon, itis possible to slide the forks on the longitudinal ribs 68.

The levers 71, in addition to controlling the sliding movement of thefork assembly relatively to members 61, 61a are further adapted toprevent upward movement of the forks in a manner to release the forksfrom ribs 68. Thus, it is the function of each of the handles 73 of thetwo levers 71 to coact with surfaces 77 to prevent upward movement ofthe fork assembly in a manner to separate lugs 67 from ribs 68. Thoseskilled in the art will appreciate that the retention of the forkassembly and the sliding movement thereof is conventional. However, sofar as I know, it has never been proposed to adjust the sliding of thefork assembly through means that are also effective to prevent themovement of the fork assembly away from the carriage.

In order to effect lifting movement of the carriage of my truck, Iutilize the vertical movement of the secondary uprights relatively tothe primary uprights. Through the arrangement I shall describepresently, I am able to mount the hydraulic rams that do the lifting sothat those rams will be extremely close to the upright assemblies whileat the same time making possible a balanced lifting of the carriage ofmy truck. Thus, I utilize the rams for lifting directly the secondaryuprights as I have already indicated, the pistons of the rams bearingagainst the plate 30 of the secondary upright assembly as described inconnection with Fig. and as is well shown in Figs. 2 and 3. Foraccomplishing the actual lifting of the load carriage I employ a paireofchains, one on each side of the carriage. Each chain is designated inthe drawings by reference numeral 80, one end of each chain beingsecured to a coupling member 81 that is formed at the end of a rod 82fitting in the opening of a sleeve 83, as best seen in Fig. 3, therebeing a sleeve 83 formed integrally with a portion 57a on each of theside carriage plates 57.

The opposed end of each of the chains 80 may be suitably secured to theprimary uprights at any desired point, each of the chains being reavedover a sheave 85, Figs. 1 and 3. There are two of these sheaves 85, oneat each side of the secondary upright assembly 11. The sheaves aresupported on the secondary upright assembly by shafts 86, the saidshafts being carried by vertical plates 29 already referred to inconnection with Fig. '10. It will be noted, particularly from Figs. 3and 10, that the sheaves are mounted in olfset relation to the pistons32 of the rams 33. This is necessary because, while it is desirable toget the rams over to each side of the truck as far as possible, thechains 80 must be mounted where they may lie in line with sleeves 83 ofthe plates 57 of the carriage. Of course, with the construction so setforth, the transmission of the lift to the secondary upright assembly 11will be fully balanced, while at the same time the transmission of liftto the carriage through the chain will also be fully balanced since thesheaves 85 are properly spaced on the secondary upright assembly. Inthis way, I obtain a balanced lifting of the load carriage while at thesame time utilizing rams that are offset relative to the axis ofoperation of the chains. This is an exceedingly important feature of myinvention as those skilled in the art will appreciate.

It will further be noted that each of the sheaves 85 is equipped withflanges that are grooved for the mounting of hydraulic hose and electricwires. Thus, the electric wires are designated by reference numeral 91and the hydraulic hose by numeral 92. The purpose of this constructionis to be able to carry hydraulic hose and electric wires from the truckproper to the carriage. In this way, attachments carried by the carriagemay be controlled electrically and operated hydraulically by fluid inthe hose 92.

Those skilled in the art will now appreciate that I have a secondaryupright assembly fully nested in a primary upright assembly, but that Iam still able to utilize rollers for accepting the thrusts developedbetween the upright assemblies. This makes it possible for me to handleexceedingly heavy loads while at the same time obtaining that visibilitythat is only possible through the use of nested uprights. It will alsobe apparent to those skilled in the art that I have developed anextremely efiicient and efiective means for assembling a load liftingcarriage for movement on secondary uprights and for adjusting thecarriage relatively to the secondary uprights.

Further, it will be readily appreciated that I may lift my load throughthe use of two rams that may be mounted in extremely close relation tothe upright assemblies, while yet obtaining a balanced lifting of thecarriage through chains. This mounting of the rams naturally contributesextremely good vision so that I am able to take advantage fully of thenested relation of the uprights. It is thought that the additionalfurther features including the mounting of the forks on the carriage,the pivotal mounting of the uprights, the positioning of the hydraulicrams and their retention, will all be fully and clearly understood bythose skilled in the art.

I now claim:

1. In a truck of the class described, a pair of spaced primary uprightshaving a base plate, a pair of spaced secondary uprights between saidprimary uprights, means engaging upon movement of said secondaryuprights downwardly relatively to said primary upright for mounting saidsecondary uprights for vertical movement on said primary uprights, ahydraulic ram comprising a cylinder and a piston, brackets on saidsecondary uprights adapted to embrace the cylinder of said hydraulic ramtherebetween in a position parallel to said uprights upon the insertionof said cylinder upwardly between said brackets, a cross plate at theupper end of said secondary uprights, means securing the upper end ofsaid hydraulic ram piston to said cross plate, there being an opening inthe space between the lower ends of said secondary uprights throughwhich said ram may be inserted upwardly between the embracing bracketsto bring the piston against said cross plate, and means on the baseplate of said primary uprights engaged by the lower end of the cylinderof said ram to support the ram in operating position when said secondaryuprights and cylinder are moved downwardly relatively to said primaryuprights to assemble said secondary uprights relatively to said primaryuprights.

2. In a truck of the class described, a pair of opposed spaced channeleduprights, a pair of opposed spaced plates, each of said plates having aroller fitting in one of said channels, a central carriage membersecured at its opposed ends to said pair of plates whereby to form aload carriage, said rollers supporting said carriage for verticalmovement on said channeled uprights, and means for adjusting thesecuring of said plates to said central carriage member whereby toadjust the rollers relatively to said channeled uprights.

3. In a truck of the class described, a pair of opposed spaced channeleduprights, a pair of opposed spaced plates, each of said plates having aroller fitting in one of said channels, a central carriage member, aportion on each end of said central carriage member secured relativelyto one plate whereby to form a load carriage, said rollers supportingsaid carriage for vertical movement on said channeled uprights, andmeans for adjusting one portion of the carriage member relatively to thecorresponding plate whereby to adjust relatively to said channeleduprights the rollers that support the carriage.

4. In a truck of the class described, a pair of spaced primary uprightshaving a base plate, a pair of spaced secondary uprights between saidprimary uprights, means engaging upon movement of said secondaryuprights downwardly relatively to said primary uprights for mountingsaid secondary uprights for vertical movement on said primary uprights,a hydraulic ram comprising a cylinder and a piston, brackets on saidsecondary uprights adapted to embrace the cylinder of said hydraulic ramtherebetween as said cylinder is moved vertically into a positionbetween said brackets,'means securing the upper end of the piston ofsaid hydraulic ram to said secondary uprights when said ram cylinder ismoved upwardly between said brackets, and support means on the baseplate of said primary uprights against which the lower end of thecylinder of said ram moves to support the ram in operating position whensaid secondary uprights and cylinder move downwardly relatively to saiduprights to assemble said secondary uprights to said primary uprights,said support means and the bottom of said ram cylinder being formed forrelative pivotal movement therebetween.

5. In a truck of the class described, a pair of opposed substantiallyvertical channeled primary uprights having their flanges in parallelalignment, channeled secondary uprights nested to slide within thechannels of the primary uprights, the flanges of said secondary uprightsbeing each dimensioned for predetermined looseness relatively to thespace between the inside surfaces of the flanges of the primarychanneled uprights, a load platform, means extending into the channelsof said secondary uprights for slidably supporting said load platformfor movement on said secondary uprights, said load platform adapted byits weight to bias the secondary uprights toward an angular position inthe channels of said primary uprights with the degree of angularitydetermined by the dimensioning of said secondary uprights and theirlooseness relatively to said primary uprights, a roller at the lower endof each secondary upright adapted to roll against the inside surface ofone flange of its primary upright to accept the thrust between the lowerends of said secondary uprights and the primary uprights as saidsecondaryuprights move upwardly and downwardly in said primary uprightswhile biased towards said angular position, a roller at the upper end ofeach primary upright engaging the outer surface of the flange of itssecondary upright on the opposite side of its secondary upright fromsaid one flange of the primary upright to accept the thrust between theupper ends of the primary uprights and the secondary uprights as saidsecondary uprights move upwardly and downwardly in said primary uprightswhile urged to said biased position, and power means for elfectingmovement of said load platform relative to said primary uprights.

References Cited in the file of this patent UNITED STATES PATENTS2,279,832 LeTourneau Apr. 14, 1942 2,456,320 Repke Dec. 14, 19482,595,120 Barnes Apr. 29, 1952 2,678,746 Gibson I May 18, 1954 2,679,437Pusztay May 25, 1954 2,701,031 Brumbaugh n' Feb. 1, 1955 2,746,612 WirzJuly 12, 1952

